As a technology which extracts an object from an image, a method which is referred to as a graph cut method has been proposed and used practically (refer to NPL 1)
In the graph cut method, first, a boundary of a region which configures a foreground object image to be cut out is calculated from color distribution, or a gradient of pixel color of two types of images of the foreground object image including an object which is desired to be cut out based on information which is input by a user, and a background image. In addition, the foreground object image which is desired to be cut out is extracted by cutting out an image along a calculated boundary.